The present invention relates generally to sphincterotomy, and more specifically to devices such as papillotomes and their method of use and fabrication to provide controlled bending during cutting to provide controlled cutting of the patient's sphincter.
In endoscopic sphincterotomy, sphincterotomes, and more specifically papillotomes, are used in conjunction with an endoscope to provide surgical cutting inside of a patient. For example, the Sphincter of Oddi opens into the duodenum at the Papilla of Vater, with the common bile duct and the pancreatic duct merging into a common channel, the Ampulla of Vater. A papillotome may be used to partially cut open the Papilla of Vater for treatment such as removal of common bile duct stones forming an obstruction.
Unfortunately, complications can arise from endoscopic sphincterotomy. For example, a survey was conducted by the American Society for Gastrointestinal Endoscopy in which endoscopic sphincterotomy was attempted in 5,790 patients. Of these, 393 patients had complications, and 22 patients died. This mortality rate of about 0.04 percent is serious. Major complications from endoscopic sphincterotomy include bleeding, pancreatitis, perforation, and cholangitis, with bleeding being the most common complication. The vast majority of such bleeding typically results when the retroduodenal artery is cut. The present invention enhances the control which a physician has in performing a sphincterotomy, and provides a reduced risk of inadvertent or uncontrolled cuts which may injure the patient.
Earlier papillotomes, such as disclosed in U.S. Pat. No. 4,485,812 to Harada et al. disclose a papillotome of the general type having an electrically conductive wire exposed outside of a tube to act as a cutter. A variety of such sphincterotomes with the wire formed in a bow outside the tube are known as soma or push-type sphincterotomes, as well as traction-type sphincterotomes. These devices generally are well known, but may contribute to the problem previously described. Shortcomings of this type of papillotome are discussed in U.S. Pat. No. 4,474,174 to Petruzzi, rejecting these more conventional papillotome knives as lacking precise control and providing poor control with danger to adjacent structures during cutting. Instead, the Petruzzi patent suggests an alternative approach in which, rather than having a bowed cutting wire, a pre-bent wire knife having a distal tip is advanced inside a single lumen catheter until it projects from a channel cut through the catheter wall at an angle. The wire knife is connected to a control wire which is manipulated to extend and retract the wire knife to engagement with the tissue. The control wire is fabricated from a helically twisted ribbon-shaped wire. The helically twist provides both a passage way through the lumen for the supply of contrast media, and prevents radial collapse of the catheter walls to maintain the lumen open.
Several other cutting devices have been proposed with a variety of twisted reinforcing wires or other reinforcing wires in the catheter lumen to reinforce against radial collapse to maintain the lumen open to allow fluids, such as contrast media, to be supplied to the surgical area. Such devices are illustrated in U.S. Pat. No. 4,325,374 to Komiya, in which a coiled spring is utilized to prevent lumen collapse; and U.S. Pat. No. 4,724,836 to Okada in which a reinforcing wire is disposed in a fluid lumen to prevent collapse of the lumen when the distal tip is bent. Although these various reinforcing wires may be advantageous for preventing collapse of the lumen, they are not directed to solving the problem set forth above regarding uncontrolled cutting.
One approach to this problem was conceived by Dr. Frimberger in Munich, Germany, to wedge a ribbon of spring steel into the distal 15 to 20 centimeters of the lumen of the papillotome. Unfortunately, such device presented manufacturing problems and was problematic in that the papillotome would exit the endoscope in the proper orientation only about 70 or 80 percent of the time.
The present invention overcomes the limitations of other devices and provides for a controlled, safer cutting. Furthermore, the device of the present invention exits the endoscope in the correct orientation virtually all of the time. Accordingly, the risk of complications, and the associated mortality, may be reduced. The present invention provides a specially oriented reinforcing member disposed in a second lumen in the sphincterotome. Preferably, this reinforcing member has a rectangular cross-section and runs the entire length of the lumen. Due to the rectangular cross-sectional shape, there is a greater cross-sectional moment of inertia along a bending axis than along a perpendicular axis. This provides controlled rigidity in one dimension, allowing the cutting edge of the cutter wire to be moved in a predetermined cutting plane. This cutting plane may be properly oriented with respect to the sphincter to be cut due to this controlled rigidity. Accordingly, the physician maintains a greater control during endoscopic sphincterotomy, and reduces the risk of improper cuts and the associated complications. Furthermore, the present invention is well suited for quality control manufacturing to ensure cutting in the proper plane when the device is used. Accordingly, the present invention provides a significant advance in the art.